JPH0750870Y2 - Eddy current retarder rotor structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a rotor structure of an eddy current retarder that applies deceleration braking to a vehicle.

[Prior Art] Generally, a deceleration braking device that applies stable continuous deceleration braking to a vehicle in order to prevent acceleration that occurs when the vehicle is descending a long hill and prevents burnout of a foot brake that is a main brake. An eddy current retarder is known as a (retarder) (for example, Japanese Unexamined Patent Publication No. 50-61574, “Reduction gear”). As such an eddy current retarder, the applicant first generated an eddy current in the rotor. We have developed various lightweight and compact eddy current retarders that use permanent magnets as magnetic force sources.
(For example, Japanese Patent Application No. 1-218498 and Japanese Patent Application No. 1-218498)
Figure 11 shows the outline of these eddy current retarders. As shown in the figure, the stator b is positioned on the inner peripheral side of a drum-shaped iron rotor a attached to the rotating shaft, and the stator b is supported from the fixed side with a predetermined gap from the rotor a. The stator b faces the inner peripheral surface of the rotor a and extends N in the circumferential direction.
It has a permanent magnet c in which poles and S poles are alternately arranged.

Therefore, a magnetic circuit connecting the N pole and the S pole between the adjacent permanent magnets c having different polarities of the stator b, which is the fixed side, and the rotor a, which is the rotating side, is constructed as shown by the broken line in FIG. Will be done. Therefore, when the rotor a attached to the rotary shaft rotates in the direction of the arrow d, an eddy current e that gives a braking force to the rotation of the rotor a flows on the inner peripheral surface of the rotor a as the rotor a rotates, and the rotor a The deceleration braking of the rotary shaft to which is attached will be achieved.

At this time, basically, as shown in FIG. 11, the eddy current e flowing on the inner peripheral surface of the rotor a is such that the inner peripheral surface of the rotor a facing between the magnets of the adjacent permanent magnets c of different polarities of the stator b. Of the eddy currents involved in the braking force, the current component in the axial direction of the drum-shaped rotor a is as is clear from Fleming's left-hand rule. Is. That is, in this eddy current retarder, an unrelated unnecessary current that does not directly relate to the braking force of the rotor a also flows.

Therefore, the applicant newly made an eddy current in which a braking force is improved by casting copper material g on both sides of the inner peripheral surface of the rotor a along the circumferential direction of the rotor a, as shown in FIG. A rotor structure for a rotary retarder was developed.

According to the roller structure of this eddy current retarder, the rotor a
Since the electrical resistance of the copper material g is smaller than that of the iron material forming the main body, the eddy current is concentrated on the copper material g.

It has been confirmed by the study of the present inventors that the braking force is improved by 20% or more by bridging the copper material g from this state, that is, by passing an electric current in the axial direction of the rotor a.

[Problems to be Solved by the Invention] In the rotor structure of such an eddy current type retarder, however, eddy current as energy loss flows concentrated in the copper material g at the time of braking, so that the rotor structure continues When the braking state is brought about, the copper material g generates heat at a high temperature (600 ° C. or higher).

Then, the coefficient of thermal expansion of the copper material g is larger than that of the iron rotor a main body, so that the copper material g is separated from the rotor a main body due to the difference in thermal expansion, or the copper material g is cracked. Resulting in.

In particular, under a use condition in which a braking state in which the rotor a generates heat and a braking release state in which the rotor a does not generate heat are alternately repeated,
The peeling and cracking of the copper material g remarkably progressed, which was a serious problem in terms of durability and reliability.

The object of the present invention devised in consideration of the above circumstances is to provide a rotor structure of an eddy current retarder capable of efficiently generating an eddy current in the rotor to improve the braking force and thermal durability. It is provided.

[Means for Solving the Problems] In order to achieve the above object, the rotor structure of the eddy current retarder of the present invention is such that a rotor having a magnetic force provided on a fixed side causes an eddy current to be generated on a rotating shaft. At the same time, since a groove is formed in the rotor along its circumferential direction, and a good conductor such as a ring-shaped copper which is partially cut and allows thermal expansion is detachably embedded in the groove. It is configured.

[Operation] When the rotor rotates, an eddy current that decelerates the rotation of the rotor is generated by the magnetic force of the stator provided on the fixed side, and the rotating shaft is decelerated and braked.

Here, since good conductors are embedded in the rotor along the circumferential direction thereof, the eddy currents concentrate on these good conductors. At this time, a current flows in a direction orthogonal to the above-mentioned good conductor provided along the circumferential direction of the rotor, but this current greatly contributes to the improvement of the braking force as is clear from Fleming's left-hand rule. The braking force is greatly improved.

Further, the good conductor on which the eddy current is concentrated generates heat and thermally expands. However, since the good conductor is formed in a partially cut annular shape, thermal expansion of the good conductor occurs at this cut portion. Will be acceptable.

Further, since the good conductor is removably embedded in the groove of the rotor, it can be replaced when it deteriorates due to thermal expansion.

[Embodiment] An embodiment of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, a flange portion 2 is formed on an output shaft 1 of a transmission of an automobile so as to extend outward in the radial direction of the shaft 1. The flange portion 2 is provided with a brake drum 3 for a parking brake. The eddy current type rotor 4 and the rotor 4 are fastened together by mounting bolts 5.

The rotor 4 is a conductor and a magnetic material such as Fe.
The material is formed into a drum shape, and is provided coaxially with the output shaft 1. A stator 7 is provided inside the drum-shaped rotor 4 and supported by a mission case 6 so as to be reciprocally movable in the axial direction of the drum.

The stator 7 is composed of an annular support ring 8 arranged concentrically with the output shaft 1 and a permanent magnet 9 attached on the support ring 8. Supported by. The permanent magnet 9 constituting the stator 7 is formed of a rare earth element such as neodymium in a lightweight and compact form so as to exert a strong magnetic force.
As shown in FIG. 11, a plurality of (eight to twelve) pieces are arranged at predetermined intervals so that the north pole and the south pole are alternately arranged facing the inner peripheral surface of the drum-shaped rotor 4 in the circumferential direction. ) It is provided around the support ring 8.

As shown in FIG. 1, the stator 7 including the permanent magnet 9 and the support ring 8 is sealed by a casing 11 that allows the stator 7 to reciprocate in the drum-shaped rotor 4.

The casing 11 is located on the inner peripheral side of the drum-shaped rotor 4 and is provided at a predetermined distance from the rotor 4, and the magnetic permeability portion 12 that allows the magnetism of the stator 7 to pass through and the magnetism of the stator 7 to be magnetized. And a magnetic shield portion 13 for shielding.

When the stator 7 is moved to the magnetic permeable portion 12 as shown by the solid line in FIG. 1 by using the actuator 14 attached to the casing 11, the permanent magnet 9 of the stator 7 on the fixed side and the permanent magnet 9 on the rotating side. A magnetic circuit that connects the N pole and the S pole is formed between the rotor 4 and an eddy current that gives deceleration braking to the rotation of the rotor 4 flows on the inner peripheral surface of the rotor 4 as shown in FIG. The deceleration braking of the output shaft 1, which is the shaft, is achieved.

On the other hand, when the stator 14 is moved to the magnetic shield portion 13 by the actuator 14 as shown by the broken line in FIG. 1, the stator 7 is in the magnetic shield state and the deceleration braking of the rotary shaft is released. .

The feature of this embodiment is that, as shown in FIG.
A copper ring as a good conductor is provided along the circumferential direction on the inner peripheral surface of the drum-shaped rotor 4 facing the stator 7 on the fixed side.
It is that 15 was detachably embedded. As shown in the drawing, the copper rings 15 are provided in parallel at the both ends of the inner peripheral surface of the rotor 4 over the entire circumference in the circumferential direction.

The method of burying the copper ring 15 in the inner peripheral surface of the rotor 4 is as follows.

First, as shown in FIG. 3, two grooves 16 are formed in parallel at both ends of the inner peripheral surface of the rotor 4 over the entire inner peripheral surface of the rotor 4. Then, the copper ring 15 as a good conductor shown in FIG. 4 is detachably fitted into these grooves 16 by press fitting.

That is, this copper ring 15 has a ring width 15w of the third
It is formed slightly wider than the groove width 16w of the groove 16 shown in the figure. Further, this copper ring 15 is formed such that its ring diameter 15d is slightly larger than the diameter of the groove 16 on the inner peripheral surface of the rotor 4, and the spring force is utilized to form the groove on the inner peripheral surface of the rotor 14.
It will be removably fitted in 16.

Further, as shown in FIG. 4, the copper ring 15 is formed by cutting a part of the ring 15 and connecting the cut portions in a concavo-convex shape with a predetermined gap (slit 17) therebetween. The slit 17 is formed by connecting the copper ring 15 to the groove 16 on the inner peripheral surface of the rotor 4.
It does not completely disappear after being fitted therein, and is formed so as to have the set predetermined gap even after being fitted.

Further, in this copper ring 15, when the ring 15 is fitted into the groove 16 on the inner peripheral surface of the rotor 4, the fitting position of the ring 15 is uniquely determined. Therefore, as shown in FIG.
Are formed. On the other hand, a positioning pin 19 that engages with the positioning groove 18 is provided in the groove 16 on the inner peripheral surface of the rotor 4, as shown in FIG.

Therefore, the copper ring 15 is fitted into the groove 16 while engaging the positioning groove 18 of the copper ring 15 with the positioning pin 19 of the groove 16 portion of the rotor 4, as shown in FIG.

As a result, when the copper ring 15 fitted in the groove 16 on the inner peripheral surface of the rotor 4 is viewed from the side, the copper ring 15 is formed as shown in FIG.
The positioning groove 18 and the positioning pin 19 of the groove 16 portion of the rotor 4 are engaged with each other so that the copper ring 15 does not shift in the groove 16 and move. That is, the position of the slit 17 of the copper ring 15 in the groove 16 does not change.

The operation of this embodiment having the above configuration will be described.

As shown in FIG. 1, when the stator 7 is moved to the magnetically permeable portion 12 by the actuator 14, the inner peripheral surface of the drum-shaped rotor 4 is changed due to the relative difference between the rotating rotor 4 and the fixed stator 7. As shown in FIG. 11, an eddy current is generated and the output shaft 1 to which the rotor 4 is attached is decelerated and braked.

At this time, on the inner peripheral surface of the rotor 4 in which the eddy current is generated, as shown in FIG. 2, two copper rings are embedded in parallel at both ends thereof in the circumferential direction. Since the electric resistance of the copper ring 15 is smaller than that of the rotor 4 of FIG. At this time, a current flows so as to bridge the rings 15 between the two parallel copper rings 15, that is, along the axial direction x of the drum-shaped rotor. This current greatly contributes to the improvement of the braking force as is clear from Fleming's left-hand rule, and the braking force is greatly improved.

That is, a current along the axial direction x of the drum-shaped rotor 4 that greatly contributes to the improvement of the braking force is efficiently generated, and the damping braking force is significantly improved.

Further, the copper ring 15 on which the eddy current concentrates generates heat due to the concentration of the eddy current as an energy loss, so that the copper ring 15 thermally expands.

Here, in the state where the copper ring 15 is fitted in the groove 16 on the inner peripheral surface of the rotor 4, as shown in FIG. 6, the cut portions of the cut ring 15 have a predetermined gap (slit 17). Since the copper ring 15 has thermal expansion, the expansion is absorbed by narrowing the slit 17 when the copper ring 15 thermally expands.
Therefore, the copper ring 15 does not fatigue due to thermal expansion.

Further, at this time, the copper ring 15 thermally expands,
The spring force increases as the diameter 15d of the ring 15 increases. Therefore, even when the rotor 4 rotates at high temperature and high speed, the copper ring 15 firmly adheres to the groove 16 on the inner peripheral surface of the rotor 4 and does not separate from the groove 16.

Further, as shown in FIG. 6, in the copper ring 15, since the positioning groove 18 thereof is engaged with the positioning pin 19 of the groove 16 portion of the rotor 4, the copper ring 15 shifts in the groove 16 and moves. There is nothing to do. Therefore, while the rotor 4 is rotating, the copper ring
The position of the slit 17 of 15 does not change, and the unbalanced rotation of the rotor caused by the change of the position of the slit 17 can be prevented. That is, even if the copper ring 15 thermally expands, the rotational balance of the rotor 4 can always be maintained in the optimum state.

Further, if the copper ring 15 is cracked due to thermal expansion fatigue by alternately repeating braking and braking for a long period of time, the copper ring 15 will not contact the inner peripheral surface of the rotor 4. Since it is detachably fitted in the groove 16, it is possible to replace the copper ring 15 that has undergone thermal expansion fatigue with a new copper ring 15, and the maintainability of the device becomes good.

The copper ring 15 shown in FIG. 6 may be constructed as shown in FIGS. 7 and 8. That is, the groove of the rotor 4
Not only the positioning groove 18 that engages with the 16 positioning pins 19 is formed in the copper ring 15, but also a supporting groove portion 20 that allows the thermal expansion of the copper ring 15 is formed, and the supporting groove portion 20 of the rotor 4 The positioning pin 21 may be inserted and supported from the groove 16 side.

Also, as shown in FIG. 9, the cut portion 15 of the copper ring 15 is
The x and 15y may be formed obliquely. In this case, the cut portions 15x and 15y of the ring 15 come to ride on each other at the time of thermal expansion, and the adhesion of the copper ring 15 to the groove 16 portion is further enhanced.

Further, as shown in FIG. 10, slots 22 made of copper for connecting the two copper rings 15 to each other may be provided at predetermined intervals along the circumferential direction of the ring 15. As a result, the current component flowing in the axial direction x shown in FIG. 2 for improving the braking force can be increased, and the braking force is further improved.

[Effects of the Invention] As described above, according to the present invention, the following excellent effects can be exhibited.

(1) Eddy current can be efficiently generated in the rotor, and the deceleration braking force is improved.

(2) The thermal durability of the good conductor embedded in the rotor can be improved.

(3) When the good conductor is thermally deteriorated, it can be replaced with a new one, which improves the maintainability of the device.

[Brief description of drawings]

1 is a side sectional view of an eddy current type retarder showing an embodiment of the present invention, FIG. 2 is a partial side sectional view showing a rotor structure of the eddy current type retarder shown in FIG. 1, and FIG. FIG. 4 is a partial side view of the rotor showing a groove formed in the rotor shown in FIG. 4, FIG. 4 is a perspective view showing a copper ring as a good conductor fitted in the groove shown in FIG. 3, and FIG. FIG. 6 is a side view of the copper ring, FIG. 6 is a side view of the copper ring showing a modified embodiment, and FIG. 9 is another modification. FIG. 10 is a partial side view of a copper ring showing an example, FIG. 10 is a partial perspective view of a copper ring showing still another modified embodiment, and FIG. 11 is a schematic view of an eddy current retarder previously developed by the applicant. FIG. 12 is a partial perspective view showing the rotor structure of FIG. In the figure, 1 is an output shaft which is a rotating shaft, 4 is a rotor, 7 is a stator, 15 is a copper ring as a good conductor, and 16 is a groove.

Claims (1)

[Scope of utility model registration request] 1. A rotor, in which an eddy current is generated by a stator having a magnetic force provided on a fixed side, is attached to a rotating shaft, and a groove is formed in the rotor along the circumferential direction thereof, and the groove is formed in the groove. A rotor structure for an eddy current retarder, in which a good conductor such as an annular copper member that is partially cut to allow thermal expansion is detachably embedded.